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Biomedical subjects

G J Lee

Publications and source records attributed to G J Lee.

At least 19 recordsLinked to original sources
PubMed2006

Salvage of the lower extremity free flap using cross-leg venous repair.

This retrospective study was designed to evaluate a salvage technique for free flaps suffering venous congestion by using a cross-leg vein repair in patients with venous-impaired lower extremities. Four free flap reconstructions were performed using the latissimus dorsi muscle to reconstruct soft tissue defects in the lower extremity. The recipient artery was confined to the ipsilateral leg and the venous anastomosis was performed with a long saphenous vein from the contralateral side. The legs were immobilised together by means of an external fixator. All patients were males with a mean age of 31 years. The mean time of pedicle division was 8.8 days (7-10). The mean size of the free flap was 186.5 cm(2). All flaps survived after pedicle division without venous congestion. There were no complications such as joint stiffness or donor site morbidity except for a linear scar. The cross-leg venous repair is a refinement of a salvage procedure for compromised free flaps used in the reconstruction of severe soft tissue defects in vascularly compromised lower extremities.

Accidents, Traffic↗
PubMed2005

Varying Ti-6Al-4V surface roughness induces different early morphologic and molecular responses in MG63 osteoblast-like cells.

Osteoblast response to Ti implants depends not only on the chemistry of the implant but also on the physical properties of the implant surface, such as microtopography and roughness. This study was undertaken to examine early changes in cell morphology and gene expression during the early phase of osteoblast interaction with titanium alloy (Ti-6Al-4V) surfaces of two different roughnesses. MG63 osteoblast-like cells were cultured for 2, 6, 24, and 72 h on smooth (Ra=0.18+/-0.03 microm) and rough (Ra=2.95+/-0.23 microm) Ti-6Al-4V surfaces. Changes in cell proliferation were assessed by measuring cell number after 72 h in culture. Morphological characteristics were observed by scanning electron microscopy after 2, 6, and 24 h of culture. Changes in gene expression for extracellular signal-regulated kinase 2 (Erk2), type I collagen (alpha2[I] collagen), phospholipase C-gamma2 (Plc-gamma2), and beta-actin were measured by RT-PCR after 6 and 24 h in culture. Cell number was significantly higher on the smooth surface. In scanning electron micrographs, cells on smooth Ti-6Al-4V were spherical and raised up from the surface after 2 h in culture. In contrast, cells on the rough surface adopted an irregular, elongated shape that spanned across pits in the surface. At 24 h, cells on the smooth surface had flattened, become elongate, and covered the surface. In contrast, cells on the rough surface appeared more differentiated in shape and the margins of the cells were irregular, with many processes extending out, following the contour of the surface. Of the genes examined, only Erk2 and beta-actin showed a change in expression with surface roughness. Both genes were upregulated (p<0.05) on the rough surface at 6 h. These results indicate that Ti-6Al-4V surface roughness affects osteoblast proliferation, morphology, and gene expression, and that these effects can be measured after periods as short as 2-6 h.

Alloys↗
PubMed2005

Detection of quantitative trait loci for androstenone, skatole and boar taint in a cross between Large White and Meishan pigs.

'Boar taint' is a strong perspiration-like, urine-like unpleasant odour given off upon heating or cooking of meat from some intact (uncastrated) male pigs. Data from the F(2) generation of a Large White (LW) x Meishan (MS) crossbred population were analysed to detect quantitative trait loci (QTL) for traits associated with boar taint. Fat samples from 178 intact male pigs slaughtered at 85 +/- 5 kg were analysed for the major contributors to boar taint (androstenone, indole and skatole). Fat and lean samples from cooked meat were scored for boar, abnormal and pork flavour and odour by a trained sensory panel (SP). A scan with 117 markers covering the whole genome was performed in the F(2) individuals, together with their F(1) parents and purebred grandparents. At the 5% chromosomal significance threshold (approximately equal to the genome-wide suggestive significance threshold), QTL were detected for the laboratory estimate of androstenone on chromosomes 2, 4, 6, 7 and 9. However, only on chromosome 6 were there QTL for boar flavour (BF) traits in the same or adjacent marker intervals as a QTL for the laboratory estimate of androstenone. On chromosome 14, QTL were detected for the laboratory estimates of indole and skatole, the SP score for skatole and the scores for BF in lean and BF in fat. In all five cases, the MS allele generally increased the estimate or score, compared with the LW allele, but it appeared that desirable and undesirable alleles were present in both breeds. This locus on chromosome 14 has considerable potential for use to reduce the incidence of boar taint, especially if further research can identify the causative polymorphism or strongly associated markers.

Androsterone↗
PubMed2004

A major QTL conditioning salt tolerance in S-100 soybean and descendent cultivars.

Deployment of salt tolerant cultivars is an effective approach to minimize yield loss in a saline soil. In soybean, Glycine max (L.) Merr., substantial genetic variation exists for salt response. However, breeding for salt tolerance is hampered because no economically viable screening method has been developed for practical breeding. To facilitate the development of an effective screening method for salt tolerance in soybean, the present study was conducted to determine the heritability of salt tolerance and to identify associated quantitative trait loci (QTL). F2:5 lines from the cross of 'S-100' (salt tolerant) x 'Tokyo' (salt sensitive) were evaluated in a saline field in Hyde County, N.C., USA, in 1999 and in a greenhouse located in Raleigh, N.C., USA, in 2001. S-100 and Tokyo are ancestors of popular soybean cultivars released for the southern USA. The visual salt tolerance ratings of the F2:5 lines ranged from 0 (complete death) to 5 (normal healthy appearance). The entry-mean heritability for salt tolerance was 0.85, 0.48, and 0.57 in the field (four replications), greenhouse (two replications), and combined environments, respectively. The genotypic correlation between field and greenhouse ratings was 0.55, indicating reasonably good agreement between the two screening environments. To identify QTL associated with salt tolerance, each line was characterized with RFLP markers and an initial QTL single-factor analysis was completed. These results were used to identify genomic regions associated with the trait and to saturate the selected genomic regions with SSR markers to improve mapping precision. Subsequently, a major QTL for salt tolerance was discovered near the Sat_091 SSR marker on linkage group (LG) N, accounting for 41, 60, and 79% of the total genetic variation for salt tolerance in the field, greenhouse, and combined environments, respectively. The QTL allele associated with tolerance was derived from S-100. Pedigree tracking was used to examine the association between the salt tolerance QTL and flanking SSR marker alleles in U.S. cultivars descended from S-100 or Tokyo through 60 years of breeding. The presence of alleles from S-100 at the Sat_091 and Satt237 marker loci was always associated with salt tolerance in descendants. Alleles from Tokyo for these same markers were generally associated with salt sensitivity in descendent cultivars. The strong relationship between the SSR marker alleles and salt tolerance suggests that these markers could be used for marker-assisted selection in commercial breeding.

Adaptation, Physiological↗
PubMed2001

Enantioselective binding of ofloxacin to B form DNA.

The binding affinity and binding mode of S- and R-ofloxacin, one of the quinolone antibiotics, to B form calf thymus DNA were studied in this work. The binding affinity of S-ofloxacin measured by both Stern-Volmer and Benesi-Hilderbrand methods was greater by a factor of 5 compared to R-enantiomer and the CD spectrum of the former is largely altered while that of the latter remained the same in the presence of DNA, indicating the enantiospecific binding of this drug to DNA. The binding geometry of both S- and R-ofloxacin calculated from the reduced linear dichroism was similar to norfloxacin, which is partially intercalated from the minor groove.

Animals↗
PubMed2001

Induction of a pepper cDNA encoding SAR8.2 protein during the resistance response to tobacco mosaic virus.

A cDNA library was constructed with mRNA extracted from TMV resistant hot pepper plants 24 and 48 h after inoculation by TMV. The library was screened differentially with radio-labeled cDNA synthesized with mRNA from the leaves of either TMV-inoculated or mock-inoculated hot pepper plants. CaSAR8.2 clone was one of the clones isolated by this differential screening. The predicted amino acid sequence of CaSAR8.2 has a homology of 52% similarity to that of tobacco SAR8.2 genes. Southern blot analysis showed that a multigene family of CaSAR8.2 was present in the hot pepper genome. Transcripts homologous to CaSAR8.2 accumulated abundantly in the leaves and the flowers, but little in other tissues. CaSAR8.2 gene expression was induced by avirulent pathotype TMV-P0 inoculation but not by virulent TMV-P1.2 inoculation. Effects of exogenously applied abiotic elicitors on CaSAR8.2 expression were also examined. Salicylic acid and ethephon treatments caused a rapid accumulation of CaSAR8.2 transcripts in pepper leaves and methyl jasmonate treatment slightly induced the expression of CaSAR8.2. A strain of Xanthomonas campestris pv. vesicatoria (Xcv) that contains an avirulence gene avrBs2, was infiltrated into the leaves of a pepper cultivar containing the Bs2 resistance gene. A marked induction of CaSAR8.2 gene expression was observed in Xcv-infiltrated leaves. These results suggest possible roles of CaSAR8.2 as pathogenesis-related protein against varieties of pathogens including virus and bacteria.

Amino Acid Sequence↗
PubMed2001

A hot pepper cDNA encoding a pathogenesis-related protein 4 is induced during the resistance response to tobacco mosaic virus.

Hot pepper (Capsicum annuum) plants exhibit a hypersensitive response (HR) against infection by many tobamoviruses. A clone (CaPR-4) encoding a putative pathogenesis-related protein 4 was isolated by differential screening of a cDNA library prepared from resistant pepper plant leaves inoculated with tobacco mosaic virus (TMV) pathotype P0. The predicted amino acid sequence of CaPR-4 is very similar to those of other plant PR-4s. Southern blot analysis showed that small gene families of PR-4-related sequences were present in the pepper genome. Hot pepper cultivar Bugang, resistant to TMV-P0 and susceptible to TMV-P1.2, induced CaPR-4 expression by pathotype P0 inoculation in inoculated and systemic leaves, but not by pathotype P1.2. Effects of exogenously applied abiotic elicitors upon the CaPR-4 expression were also examined. The expression of the CaPR-4 gene was stimulated by methyl jasmonate (MeJA), ethephon and wounding treatment. However, application of salicylic acid (SA) did not trigger the expression. Evidence is emerging that jasmonic acid and ethylene play key roles in the SA-independent pathways of plant-pathogen interaction. Taken together, these results suggest that the CaPR-4 gene is one of the defense-related genes conferring resistance on pepper plants by the SA-independent pathway and the cross-talk between signaling compounds, jasmonic acid and ethylene could have a great regulatory potential in a plant's defense against TMV.

Acetates↗
PubMed2001

An angiographic lesion mimicking pseudo-aneurysm in cerebral arteriovenous malformation.

In cerebral arteriovenous malformations (AVMs), a pseudo-aneurysm represents rupture site, and its presence is known as a factor for rebleeding. We report a case of cerebral AVM presenting with intracerebral haemorrhage in which cerebral angiography showed a lesion mimicking pseudo-aneurysm. Although the patient needed urgent surgical decompression, it was delayed because early haematoma evacuation would induce rebleeding from the rupture site. The authors attempted to occlude the pseudoaneurysm interventionally before surgery. After surgical excision, the lesion that was believed to be a pseudo-aneurysm was revealed as a partially thrombosed venous sac having a thick fibrous wall. In this report, the authors discuss the pitfalls in the interpretation of pseudo-aneurysms in angiographic AVM architecture.

Adolescent↗
PubMed2001

Hemangioendothelioma of the sphenoid bone: a case report.

Hemangioendothelioma is borderline or intermediate type of vascular neoplasm. Hemangioendothelioma is rare lesion that constitutes less than 0.5% of the malignant tumors of bone. We present a case of low-grade hemagioendothelioma of the skull in a 29-yr-old woman. She had pain, diplopia and exophthalmos of the left eye. Radiographic images showed a relatively well-demarcated, expansile osteolytic lesion with irregularly thickened trabeculae and calcifications in the left greater wing of sphenoid bone. Histologically, the tumor was an infiltrative vasoformative lesion. The vessels are generally well-formed with open or compressed lumina surrounded by endothelial cells showing mild atypia. It lacked frequent mitotic figures and severe atypia. Although excessive bleeding occurred during the operation, the mass was totally resected. Postoperative radiation was not necessary. She is free of disease and well 6 months postoperatively.

Adult↗
PubMed2000

The effects of chemical remediation treatments on the extractability and speciation of cadmium and lead in contaminated soils.

Two rural soils contaminated by cadmium (Cd) and lead (Pb) were used to evaluate the effect of different chemical treatments on changes in speciation and extractability of Cd and Pb, and in phytoavailability to wheat. Triplicates of seven chemical treatments were tested to compare and evaluate the remediation techniques for contaminated soils using pot experiments. Treatments applied were calcium carbonate, a high quantity of phosphate salt, hog composts, iron oxide, manganese oxide, zeolite, and unamended control. Wheat (Triticum aestivum) was planted in the different amended soils for a further one month to evaluate the effectiveness of treatments on uptake of Cd and Pb by the wheat shoots. Results indicated that addition of calcium carbonate, manganese oxide, or zeolite reduces the extractability of Cd or Pb in both soils, and significantly reduce the uptake of Cd and Pb by wheat shoots. Changes in the extractability and metal sequential fractionations indicate that the exchangeable (or available) form of Cd and Pb in two soils can be transformed into unavailable forms after these amendments.

Biological Availability↗
PubMed2000

Amine group of guanine enhances the binding of norfloxacin antibiotics to DNA.

The binding mode of norfloxacin, a quinolone antibacterial agent, in the synthetic polynucleotides poly[d(G-C)2], poly[d(I-C)2] and poly[d(A-T)2] was studied using polarized light spectroscopy, fluorescence spectroscopy and melting profiles. The absorption, circular and linear dichroism properties of norfloxacin are essentially the same for all the complexes, and the angle of electric transition dipole moment I and II of norfloxacin relative to the DNA helix axis is measured as 68-75 degrees for all complexes. These similarities indicate that the binding mode of norfloxacin is similar for all the polynucleotides. The decrease in the linear dichroism (LD) magnitude at 260 nm upon binding norfloxacin, which is strongest for the norfloxacin-poly[d(G-C)2] complex, and the identical melting temperature of poly[d(A-T)2] and poly[d(I-C)2] in the presence and absence of norfloxacin rule out the possibility of classic intercalation and minor groove binding. However, the characteristics of the fluorescence emission spectra of norfloxacin bound to poly[d(A-T)2] and to poly[d(I-C)2] are similar but are different to that of norfloxacin bound to poly[d(G-C)2]. As the amine group of the guanine base protrudes to the minor groove, this result strongly suggests that norfloxacin binds in the minor groove of B-form DNA in a nonclassic manner.

Animals↗
PubMed2000

A small heat shock protein cooperates with heat shock protein 70 systems to reactivate a heat-denatured protein.

Small heat shock proteins (sHsps) are a diverse group of heat-induced proteins that are conserved in prokaryotes and eukaryotes and are especially abundant in plants. Recent in vitro data indicate that sHsps act as molecular chaperones to prevent thermal aggregation of proteins by binding non-native intermediates, which can then be refolded in an ATP-dependent fashion by other chaperones. We used heat-denatured firefly luciferase (Luc) bound to pea (Pisum sativum) Hsp18.1 as a model to define the minimum chaperone system required for refolding of a sHsp-bound substrate. Heat-denatured Luc bound to Hsp18.1 was effectively refolded either with Hsc/Hsp70 from diverse eukaryotes plus the DnaJ homologs Hdj1 and Ydj1 (maximum = 97% Luc reactivation with k(ob) = 1.0 x 10(-2)/min), or with prokaryotic Escherichia coli DnaK plus DnaJ and GrpE (100% Luc reactivation, k(ob) = 11.3 x 10(-2)/min). Furthermore, we show that Hsp18.1 is more effective in preventing Luc thermal aggregation than the Hsc70 or DnaK systems, and that Hsp18.1 enhances the yields of refolded Luc even when other chaperones are present during heat inactivation. These findings integrate the aggregation-preventive activity of sHsps with the protein-folding activity of the Hsp70 system and define an in vitro system for further investigation of the mechanism of sHsp action.

Animals↗
PubMed1997

A small heat shock protein stably binds heat-denatured model substrates and can maintain a substrate in a folding-competent state.

The small heat shock proteins (sHSPs) recently have been reported to have molecular chaperone activity in vitro; however, the mechanism of this activity is poorly defined. We found that HSP18.1, a dodecameric sHSP from pea, prevented the aggregation of malate dehydrogenase (MDH) and glyceraldehyde-3-phosphate dehydrogenase heated to 45 degrees C. Under conditions in which HSP18.1 prevented aggregation of substrates, size-exclusion chromatography and electron microscopy revealed that denatured substrates coated the HSP18.1 dodecamers to form expanded complexes. SDS-PAGE of isolated complexes demonstrated that each HSP18.1 dodecamer can bind the equivalent of 12 MDH monomers, indicating that HSP18.1 has a large capacity for non-native substrates compared with other known molecular chaperones. Photoincorporation of the hydrophobic probe 1,1'-bi(4-anilino)naphthalene-5,5'-disulfonic acid (bis-ANS) into a conserved C-terminal region of HSP18.1 increased reversibly with increasing temperature, but was blocked by prior binding of MDH, suggesting that bis-ANS incorporates proximal to substrate binding regions and that substrate-HSP18.1 interactions are hydrophobic. We also show that heat-denatured firefly luciferase bound to HSP18.1, in contrast to heat-aggregated luciferase, can be reactivated in the presence of rabbit reticulocyte or wheat germ extracts in an ATP-dependent process. These data support a model in which sHSPs prevent protein aggregation and facilitate substrate refolding in conjunction with other molecular chaperones.

Amino Acid Sequence↗
PubMed1997

Expression and native structure of cytosolic class II small heat-shock proteins.

Higher plants synthesize small heat-shock proteins (smHSPs) from five related gene families. The class I and II families encode cytosolic smHSPs. We characterized the class II smHSPs of pea (Pisum sativum) and compared them with class I smHSPs. Antibodies against recombinant HSP17.7, a class II smHSP, recognized four heat-inducible 17- to 18-kD polypeptides and did not cross-react with class I smHSPs. On sucrose gradients the class II smHSPs sedimented primarily at 8 Svedberg units, indicating that they are components of large complexes similar in size to class I smHSP complexes. However, the class I and II complexes were readily distinguishable by nondenaturing polyacrylamide gel electrophoresis and isoelectric focusing. Nondenaturing immune precipitations using anti-HSP17.7 or anti-HSP18.1 (a class I smHSP) antiserum provide further evidence that the class I and II smHSPs exist in different complexes, composed primarily of smHSPs. Recombinant HSP17.7 and HSP18.1 formed complexes of sizes similar to those formed in vivo. When these two smHSPs were mixed, denatured with urea, and then dialyzed, the distinct class I and II complexes again formed, each containing only HSP18.1 or HSP17.7. Thus, cytosolic smHSPs from two related gene families expressed simultaneously form distinct complexes in vivo, suggesting that they have subtly different functions.

Antibody Specificity↗
PubMed1995

Structure and in vitro molecular chaperone activity of cytosolic small heat shock proteins from pea.

Plants synthesize several classes of small heat shock proteins ranging in size from 15 to 30 kDa. Two conserved classes, designated class I and class II, are localized to the cytosol. Recombinant HSP18.1 and HSP17.7, representing class I and class II proteins from pea, respectively, were expressed in Escherichia coli and purified. Non-denaturing polyacrylamide gel electrophoresis and electron microscopy demonstrated that the purified proteins formed discretely sized, high molecular weight complexes. Sedimentation equilibrium analytical ultracentrifugation revealed that the HSP18.1 and HSP17.7 complexes were composed of approximately 12 subunits. Both proteins were able to enhance the refolding of chemically denatured citrate synthase and lactate dehydrogenase at stoichiometric levels in an ATP-independent manner. Furthermore, HSP18.1 and HSP17.7 prevented aggregation of citrate synthase at 45 degrees C and irreversible inactivation of citrate synthase at 38 degrees C. HSP18.1 also suppressed aggregation of lactate dehydrogenase at 55 degrees C. These findings demonstrate that HSP18.1 and HSP17.7 can function as molecular chaperones in vitro.

Citrate (si)-Synthase↗